Zinc-finger nucleases (ZFNs) are a class of targetable DNA cleavage reagents that have been widely adopted for gene-targeting applications. ZFN-induced double-strand breaks (DSBs) can be repaired through homologous recombination, leading to targeted mutagenesis, or through nonhomologous end joining, resulting in targeted gene replacement. The article reviews the history of ZFN development, their applications in various organisms, and the challenges in designing and selecting ZFNs. It highlights the importance of understanding DNA repair mechanisms to optimize ZFN performance and discusses the prospects for future applications, including human gene therapy. The article also addresses the limitations of ZFNs, such as off-target cleavage, and the need for further research to improve specificity and efficiency.Zinc-finger nucleases (ZFNs) are a class of targetable DNA cleavage reagents that have been widely adopted for gene-targeting applications. ZFN-induced double-strand breaks (DSBs) can be repaired through homologous recombination, leading to targeted mutagenesis, or through nonhomologous end joining, resulting in targeted gene replacement. The article reviews the history of ZFN development, their applications in various organisms, and the challenges in designing and selecting ZFNs. It highlights the importance of understanding DNA repair mechanisms to optimize ZFN performance and discusses the prospects for future applications, including human gene therapy. The article also addresses the limitations of ZFNs, such as off-target cleavage, and the need for further research to improve specificity and efficiency.